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TECHNICAL REPORTS

Organic Compounds in the Environment

Organic Manure and Urea Effect on Metolachlor Transport through Packed Soil Columns

Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi 110 012, India

^* Corresponding author (Drneerasingh{at}yahoo.com).

Received for publication October 26, 2002.

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Application of organic manure (OM) amendments and nitrogen fertilizers can affect the sorption and movement of pesticides in soil. This study summarizes the sorption and leaching of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylphenyl)acetamide] in soils after cow (Bos taurus) manure (2.5 and 5.0%) and urea (60 and 120 kg N ha^-1) amendments in batch and column experiments. Both cow manure and urea applications increased metolachlor sorption in soils. The values of the Freundlich adsorption parameter K_f(1/n) for treatments T0, T1 (OM), and T2 (OM) were 2.31, 3.32, and 3.96 in Soil 1; 2.02, 2.77, and 3.32 in Soil 2; and 1.10, 1.46, and 2.02 in Soil 3, respectively. Similarly, K_f(1/n) values for treatment T1 (urea) and T2 (urea) were 2.37 and 2.84 in Soil 1; 2.16 and 2.83 in Soil 2; and 1.50 and 1.70 in Soil 3, respectively. Column leaching studies using Soil 1 indicated that OM application drastically reduced the metolachlor leaching losses from 50% (natural soil) to <1.0% (5.0% OM amendment). Likewise, urea application also decreased metolachlor mobility and leaching losses in columns treated with 60 and 120 kg N ha^-1 urea were 33 and 20%, respectively. The reduction in the metolachlor leaching losses was achieved through the increase in the sorption capability of the OM- and urea-amended soil. Therefore, coapplication of metolachlor with cow manure or urea fertilizers will not enhance metolachlor mobility and reduces metolachlor leaching losses in low-organic-matter soil.

Abbreviations: DOC, dissolved organic carbon • OC, organic carbon • OM, organic manure

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
METOLACHLOR IS A SELECTIVE HERBICIDE used for premergence control of annual grasses and broadleaf weeds. Contamination of water resources by pesticide usage has caused public awareness about the quality of drinking water and pollution potential. Water resources may become contaminated by the downward movement (leaching) and runoff (lateral) of soil-applied pesticides. Recent studies addressing the monitoring of pesticides in surface and subsurface water have demonstrated the presence of metolachlor residue (Goodrich et al., 1991; Koterba et al., 1993; Funari et al., 1995; Gaynor et al., 1995; Traub-Eberhard et al., 1995; Sensemann et al., 1997). Peak metolachlor concentration in subsurface drain water discharge of experimental plots ranged from 0.1 mg L^-1 (Traub-Eberhard et al., 1995) to more than 100 mg L^-1 (Gaynor et al., 1995). The USEPA health advisory level of metolachlor for drinking water is 10 µg L^-1.

To assess metolachlor transport to ground water, it is necessary to identify factors involved in the transport. Previous studies have shown that metolachlor transport is influenced by climatic factors, such as timing of rainfall after application (Southwick et al., 1990) and total volume and rate of water application (Sanchez-Martin et al., 1995), and soil properties such as physical structure (Novak et al., 2001) and clay and organic carbon (OC) content. However, among various soil properties, OC content is the single largest factor that has maximum influence on metolachlor adsorption and mobility in soil (Wood et al., 1987; Kruger et al., 1996, Wang et al., 1999, Singh et al., 2002). Thus, metolachlor is susceptible to leaching losses when applied to a coarse-textured soil with low OC content. Therefore, application of OM to low-sorptivity soils can be a promising method to reduce pesticide leaching.

Application of organic carbon in the form of manure, sludge, or crop residues is a common soil management practice followed in agriculture. Generally, addition of OM increases the adsorption of pesticides and decreases their subsequent mobility in the soil profile (Dao, 1991; Guo et al., 1993; Arienzo et al., 1994; Sanchez-Camazano et al., 1997; Cox et al., 1997). Guo et al. (1991)( 1993) studied the sorption of alachlor and atrazine on soils, freshly amended with carbon-rich waste material, and found that the adsorption coefficient for the herbicides was higher in amended soils compared with unamended soils. These results were further confirmed by Barriuso et al. (1997) for eight pesticides in freshly amended soils and Sluszny et al. (1999) in freshly amended and incubated soils. However, there are several instances when application of organic carbon amendments (sewage sludge or compost) resulted in the increased mobility of pesticides, such as atrazine, terbuthylazine, bromacil, or carbofuran (Graber et al., 1995, 2001; Worrell et al., 2001), due to increase in dissolved organic carbon (DOC) content in the soil solution, which complexes with the pesticides and serves as a vehicle for the transport of pesticides to lower soil layers.

Another agronomic practice that can affect the mobility of pesticide through soil layers is the application of nitrogen fertilizers. Liu et al. (1995a)(b) reported that addition of ammonia fertilizers increased the soil pH and DOC concentration resulting in a decrease in atrazine adsorption and an increase in desorption. This led to greater leaching of atrazine through undisturbed soil columns.

The objective of this study was to investigate the effect of cow manure and urea application, common agronomic practices, on metolachlor adsorption and its mobility through packed columns.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Soils
The soils used in the present study were collected from the experimental farms of the Indian Agricultural Research Institute, New Delhi (Soil 1), Pantnagar (Soil 2), and Punjab Agricultural University, Ludhiana (Soil 3). The soil samples were collected from the 0- to 15-cm soil profile, air-dried, and ground to pass through a 2-mm sieve. Before the study, soil samples were stored in plastic bags at room temperature. Physicochemical characteristics of the soils, which were determined using standard methods, are represented in Table 1. Soil pH was determined in a 1:1.25 soil to water suspension using a glass electrode (Jackson, 1967), organic carbon content by the Walkley–Black method (Walkley and Black, 1934), and soil mechanical fractions by the hydrometer method (Black et al., 1982). The original soil was referred as T0. The cow manure was locally purchased. The physicochemical characteristics of cow manure included a pH of 6.3 and organic carbon of 21.3%. The total carbon, nitrogen, and hydrogen contents of the manure were determined by elemental analysis and were 25.3, 6.7, and 5.8%, respectively.

Adsorption Experiment
The organic carbon amendment using the cow manure was performed by thoroughly mixing the original soils with air-dried cow manure at 2.5 and 5.0% levels. The manure-amended soils were passed through a 2-mm sieve to ensure thorough mixing of soil and manure. The samples of the amended soil so obtained were labeled as T1 (OM) and T2 (OM), respectively.

Experimental data on sorption in unamended and OM-amended soils was obtained as follows: 5 g of the soil samples [T0, T1 (OM), and T2 (OM)] and 25 mL aqueous solution of metolachlor in 50-mL glass stoppered centrifuge tubes were equilibrated on an end-over-end shaker for 2 h. The kinetics of metolachlor sorption clearly indicated that equilibrium was attained after 2 h of shaking (results not shown). The initial metolachlor concentration ranged between 2 and 20 mg L^-1. Four different metolachlor concentrations were used and each concentration was replicated three times. After equilibration, the soil–water suspension was centrifuged at 1500 rpm for 15 min and metolachlor concentration was determined in the supernatant. The amount of metolachlor sorbed was calculated from the difference between the initial and final solution concentrations. Mass balance calculation of metolachlor indicated that metolachlor was stable in the soil during 2 h of equilibration.

To study the effect of urea application on metolachlor sorption, 5-g soil samples in 50-mL glass stoppered centrifuge tubes were mixed with 10 mL aqueous solution of urea. The urea was applied at rates of 60 and 120 kg N ha^-1 and treatments were labeled as T1 (urea) and T2 (urea), respectively. Unamended original soils (T0) were supplemented with 10 mL distilled water and served as control. Further, samples T0, T1 (urea), and T2 (urea) were supplemented with 15 mL aqueous solution of metolachlor so that the final metolachlor concentration in all three treatments ranged between 2 and 20 mg L^-1. Sorption was studied in a similar manner as mentioned above. The effect of cow manure and urea applications on soil pH and DOC content (Kalembasa and Jenkinson, 1973) was also measured.

Column Experiment
Columns (30-cm length x 6-cm i.d.) were constructed from polyvinyl chloride (PVC) pipe. The PVC columns rested in Buchner funnels fitted with a 0.60-µm nylon membrane to reduce the dead end volume. Only Soil 1 was used for the column experiment. The natural (T0) and cow manure–amended soils [T1 (OM) and T2 (OM)] were added to the columns in small increments (approximately 50 g) and after each addition the soil was compacted with equal force to obtain a column of uniform compactness. The columns were packed to bulk densities of 1.46, 1.40, and 1.36 kg L^-1, respectively. The pore volume for each column type was calculated from the difference of mass of the soil in a fully saturated column and oven-dry mass of the soil. The values so obtained were 360, 365, and 370 mL for samples T0, T1 (OM), and T2 (OM), respectively. One day before chemical application the columns were pretreated with 500 mL of distilled water to minimize the variation in soil water content between the columns. Water was allowed to drain naturally. Metolachlor (1.875 mg) was applied to the column surface in 2.5 mL acetone in a drop-wise manner and an even metolachlor distribution was assured. This treatment of metolachlor was equivalent to an application rate of 3.8 kg ha^-1 (approximately double of normal dose). After herbicide application, the columns were left overnight.

Columns for the urea experiment using natural soil were constructed in a manner as explained above. The columns were packed to a bulk density of 1.46 kg L^-1 and the pore water content was 360 mL and was same for untreated and urea-treated columns. Columns were saturated with 500 mL distilled water. Urea treatments were 0, 0.6, and 1.2 mg N cm^-2. These doses of urea were equivalent to the field application rates of 60 and 120 kg N ha^-1. A 2.5-mL aliquot of water containing 35 or 70 mg of urea was applied drop-wise on the column surface and these treatments were called T1 (urea) and T2 (urea), respectively. The untreated control was labeled T0. Following the urea treatment, metolachlor (1.875 mg) was applied.

Before leaching, the column surfaces were covered with a 0.5-cm DOC-free sand layer to minimize the disturbance of soil and to provide an even distribution of leaching water. One day after herbicide application columns were leached with 1000 mL of distilled water. The water was applied on the column surface at a rate of 100 mL h^-1 and natural drainage was allowed. The application rate allowed a water head of approximately 1 cm on the soil surface throughout the leaching. The leachate fractions were collected in approximately 50-mL portions and were analyzed for the metolachlor concentration. Leachate pH and DOC content were also determined. Each column type was replicated twice.

Herbicide Extraction and Analysis
After leaching, soil columns were dissected into 5-cm increments. Each soil section was allowed to air-dry for 48 h. The air-dry samples were transferred to 500-mL stoppered conical flasks and 200 mL hexane was added. The samples were equilibrated on a rotary shaker for 2 h and 50 g of anhydrous Na₂SO₄ was added to each flask. Metolachlor was quantified by gas chromatography (GC) on a Hewlett-Packard (Palo Alto, CA) Model 3480 equipped with a ⁶³Ni electron capture detector (ECD) and fitted with an HP-1 column (10-m length x 0.50-mm i.d. x 2.53-µm film thickness). The operating conditions were: column, 175°C; injector, 300°C; detector, 300°C; carrier gas (nitrogen) flow rate, 45 mL min^-1. The detection limit for metolachlor was 0.1 µg. Metolachlor recovery from soil was more than 80%.

Metolachlor residues from the water samples were extracted by shaking a 5-mL sample with 5 mL hexane for 1 min. After shaking, the sample was allowed to stand for 1 min and 1 g of anhydrous Na₂SO₄ was added to each tube to remove any trace of moisture from the hexane fraction. Metolachlor residues in the hexane fraction were quantified using GC as mentioned above. Metolachlor recovery from water samples was more than 90%.

	RESULTS AND DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Adsorption Experiment
Adsorption isotherms for metolachlor in soils are shown in Fig. 1 . The adsorption data were fitted to the Freundlich adsorption equation:

where X is the amount of metolachlor adsorbed (mg kg^-1 soil), C is the equilibrium concentration of metolachlor (mg L^-1), and K_f and 1/n are the constants. The Freundlich constant K_f represents the amount of metolachlor adsorbed at an equilibrium concentration of 1 mg L^-1. The constant 1/n is the measure of the intensity of sorption and reflects the degree to which sorption is the function of herbicide concentration. The values of constants K_f and 1/n are presented in Table 2. The values of the correlation coefficient in all the cases were very high (r² > 0.953), indicating that the Freundlich adsorption equation satisfactorily explained the results of metolachlor sorption in natural and cow manure– or urea-amended soils and were significant at 99% level.

View larger version (29K): [in this window] [in a new window]   Fig. 1. Metolachlor sorption isotherms in natural, cow manure–, and urea-amended soils.

Column Experiment
Figure 2 shows the percolation (breakthrough and cumulative) curves of metolachlor in natural (T0) and cow manure–amended [T1 (OM) and T2 (OM)] columns of Soil 1. The results indicate that addition of OM at 2.5 and 5.0% levels drastically reduced the metolachlor movement in packed soil columns. Organic manure application affected both breakthrough time and peak maxima concentration of metolachlor from the soil column. In natural soil columns (T0) metolachlor breakthrough occurred after passing 1.53 pore volumes of water and maximum concentration of metolachlor was obtained after percolating 1.86 pore volumes of water. However, adding 2.5% cow manure to the soil significantly reduced the downward mobility of metolachlor and its breakthrough occurred in the fraction obtained after passing 2.02 pore volumes of water. The metolachlor peak maximum concentration was also reduced by nearly 50%. Likewise, a further increase in cow manure addition to 5.0% [T2 (OM)] further slowed metolachlor movement and its breakthrough occurred after passing 2.36 pore volumes. There was no significant difference in the total amount of leachate collected from the natural and cow manure–treated soil columns (Table 4). However, cow manure application reduced the pH of leachate collected from T1 (OM) and T2 (OM) columns by 0.2 and 0.3 units, respectively. Also, compared with the natural soil column, DOC content of the leachate was 2.7 and 4.8 times higher for T1 (OM) and T2 (OM) columns, respectively, than for the natural soil column (T0). Even after an increase in DOC of the leachate, metolachlor movement was slow in cow manure–amended columns. This further proves that metolachlor was bound to bulk-phase organic matter. The decrease in metolachlor movement in organic matter–amended soils is in agreement with the results of the batch experiment.

View larger version (22K): [in this window] [in a new window]   Fig. 2. (a) Breakthrough and (b) cumulative elution curves of metolachlor in unamended and cow manure–amended soil columns. The term C is the amount of metolachlor in the leachate fraction while C0 is the amount applied to the column.

View larger version (23K): [in this window] [in a new window]   Fig. 3. (a) Breakthrough and (b) cumulative elution curves of metolachlor in unamended and urea-amended soil columns. The term C is the amount of metolachlor in the leachate fraction while C0 is the amount applied to the column.

After leaching of the columns, they were dissected in 5-cm sections and the amounts of metolachlor left in soil after leaching were estimated. Metolachlor distribution in cow manure– and urea-amended columns was quite different from the natural soil columns (Fig. 4) . Metolachlor leached up to a 30-cm depth in both unamended and cow manure– or urea-amended soil columns and the amount of metolachlor recovered from the top soil layer (0–10 cm) was nearly the same in all column types. However, greater amounts of herbicide were retained in the lower soil layers in the cow manure– and urea-amended columns compared with the unamended columns. Also, metolachlor movement was not affected by the increase in the DOC content of the cow manure–amended soil columns. This study indicates that cow manure and urea amendments may not enhance metolachlor leaching and indeed significantly reduced the leaching losses of herbicide. The inverse relationship between the sorption parameter K_f(1/n) and the percentage of metolachlor recovered from the unamended and cow manure– or urea-amended columns suggests that sorption is the key process controlling the movement of metolachlor; however, in field situations biological degradative forces play an important role.

View larger version (39K): [in this window] [in a new window]   Fig. 4. Distribution of metolachlor in (a) cow manure– and (b) urea-amended soil columns.

	CONCLUSIONS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

	REFERENCES

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 

• Arienzo, M., M. Sanchez-Camazano, M.J. Sanchez-Martin, and T. Crisanto. 1994. Influence of exogenous organic matter in the mobility of diazinon in soils. Chemosphere 29:1245–1252.
• Barriuso, E., S. Houot, and C. Serrowiltling. 1997. Influence of compost addition to soil on the behaviour of herbicides. Pestic. Sci. 49:65–75.
• Black, C.A., D.D. Evans, J.L. White, L.E. Ensiminger, and F.E. Clark. 1982. Methods of soil analysis. 2nd ed. Agron. Monogr. 9. ASA and SSSA, Madison, WI.
• Cox, L., R. Celis, M.C. Hermosin, A. Becker, and J. Cornejo. 1997. Porosity and herbicide leaching in soils amended with olive-mill wastewater. Agric. Ecosyst. Environ. 56:151–161.
• Dao, T.H. 1991. Field decay of wheat straw and its effect on metribuzin and s-ethyl metribuzin sorption and elution from crop residues. J. Environ. Qual. 20:203–208.
• De Coninck, F. 1980. Major mechanisms in the formation of spodic horizons. Geoderma 24:101–128.
• Funari, E., L. Donali, D. Sandroni, and M. Vighi. 1995. Pesticide levels in groundwater: Value and limitations of monitoring. p. 3–44. In M. Vighi and E. Funari (ed.) Pesticide risk into groundwater. CRC Press, Boca Raton, FL.
• Gaynor, J.D., D.C. Mactavish, and W.I. Findlay. 1995. Atrazine and metolachlor loss in surface and subsurface runoff from three tillage treatments in corn. J. Environ. Qual. 24:246–256.[Abstract/Free Full Text]
• Ghosh, K., and M. Schnitzer. 1980. Macromolecular structures of humic substances. Soil Sci. 129:266–276.
• Gonzalez-Pradas, E., M. Villafrance-Sanchez, M. Fernandez-Perez, M. Socias-Viciana, and M.D. Vrena-Anata. 1998. Sorption and leaching of diuron on natural and peat-amended calcareous soils from Spain. Water Res. 32:2814–2820.
• Goodrich, J.A., W.L. Benzamin, and M.C. Robert. 1991. Drinking water from agriculturally contaminated groundwater. J. Environ. Qual. 20:707–717.[Abstract/Free Full Text]
• Graber, E.R., I. Dror, F.C. Bercovich, and M. Rosner. 2001. Enhanced transport of pesticides in a field trial treated with sewage sludge. Chemosphere 44:805–811.[Medline]
• Graber, E.R., Z. Gerstl, E. Fischer, and U. Mingelgrin. 1995. Enhanced transport of atrazine under irrigation with effluent. Soil Sci. Soc. Am. J. 59:1513–1519.[Abstract/Free Full Text]
• Guo, L., T.J. Bicki, A.S. Felsot, and T.D. Hinesly. 1991. Effect of carbon rich waste material on the movement and adsorption of atrazine in a sandy coarse-textured soil. Environ. Toxicol. Chem. 10:1273–1282.
• Guo, L., T.J. Bicki, A.S. Felsot, and T.D. Hinesly. 1993. Sorption and movement of alachlor in soils modified by carbon rich waste. J. Environ. Qual. 22:186–194.[Abstract/Free Full Text]
• Jackson, M.L. 1967. Soil chemical analysis. Prentice Hall, New Delhi, India.
• Kalembasa, S.J., and D.S. Jenkinson. 1973. A comparative study of titrimetric and gravimetric method for the determination of organic carbon in soil. J. Sci. Food Agric. 24:1085–1090.[ISI]
• Koterba, M.T., W.S.L. Banks, and R.J. Shedlocks. 1993. Pesticides in shallow groundwater in the Delmarva Peninsula. J. Environ. Qual. 22:500–518.[Abstract/Free Full Text]
• Kruger, E.L., B. Zhu, and J.R. Coats. 1996. Relative mobility of atrazine, atrazine degradates, metolachlor and simazine in soils from Iowa. Environ. Toxicol. Chem. 15:691–695.
• Liu, Z., S.A. Clay, D.E. Clay, and S.S. Harper. 1995a. Ammonia fertilizer influences atrazine adsorption–desorption characteristics. J. Agric. Food Chem. 43:815–819.
• Liu, Z., S.A. Clay, D.E. Clay, and S.S. Harper. 1995b. Ammonia impact on atrazine leaching through undisturbed soil columns. J. Environ. Qual. 24:1170–1173.[Abstract/Free Full Text]
• Novak, S.M., J.M. Portal, and M. Schiavon. 2001. Effect of soil type upon metolachlor losses in subsurface drain. Chemosphere 42:234–244.
• Sanchez-Camazano, M., E. Iglesias-Jimenez, and M.J. Sanchez-Martin. 1997. City refuse compost and sodium dodecylsulphate as modifier of diazinon leaching in soil. Chemosphere 35:3003–3012.
• Sanchez-Martin, M.J., T. Crisanto, L.F. Lorenzo, M. Arienzo, and M. Sanchez-Camazano. 1995. Influence of leaching rates on ¹⁴C-metolachlor mobility. Bull. Environ. Contam. Toxicol. 54:562–569.[Medline]
• Schnitzer, M. 1986. Binding of humic substances by soil mineral colloids. p. 77–101. In P.M. Huang and M. Schnitzer (ed.) Interaction of soil minerals with natural organics and microbes. SSSA Special Publ. 17. SSSA, Madison, WI.
• Sensemann, S.A., T.L. Lavy, J.D. Mattice, E.E. Gbur, and W.S. Briggs. 1997. Trace level of pesticide detection in Arkansas surface waters. Environ. Sci. Technol. 31:395–401.
• Singh, N., H. Kloeppel, and W. Klein. 2002. Transport of metolachlor and terbuthylazine in intact and packed soil columns. Chemosphere 47:409–415.[Medline]
• Sluszny, C., E.R. Graber, and Z. Gerstl. 1999. Sorption of s-triazine herbicides in organic matter amended soils: Fresh and incubated systems. Water Air Soil Pollut. 115:395–410.
• Socias-Viciana, M., M. Fernandez-Perez, M. Villafrance-Sanchez, E. Gonzalez-Pradas, and F. Flores-Cespedes. 1999. Sorption and leaching of atrazine and MCPA in natural and peat-amended calcareous soils from Spain. J. Agric. Food Chem. 47:1236–1241.[ISI][Medline]
• Southwick, L.M., G.H. Willis, R.L. Bengston, and T.J. Lormand. 1990. Atrazine and metolachlor in subsurface drain water in Louisiana. J. Irrig. Drain. Eng. 116:16–23.
• Traub-Eberhard, U., K.P. Henschel, W. Kordel, and W. Klein. 1995. Influence of different field sites on pesticide movement into subsurface drain. Pestic. Sci. 43:121–129.
• Walkley, A., and A.I. Black. 1934. An examination of the Degtjarett method for determination of soil organic matter and proposed modification of the chromic acid titration method. Soil Sci. 37:29–38.
• Wang, Q., Y. Weichun, and W. Liu. 1999. Adsorption of acetanilide herbicides on soils and its correlation with soil properties. Pestic. Sci. 55:1103–1108.
• Wood, L.S., H.D. Scott, D.B. Marx, and T.L. Lavy. 1987. Variability in sorption of metolachlor on a Captina silt loam. J. Environ. Qual. 16:251–256.
• Worrell, F., M. Fernandez-Perez, A.C. Johnson, F. Flores-Cesperedes, and E. Gonzalez-Pradas. 2001. Limitations on the role of incorporated organic matter in reducing pesticide leaching. J. Contam. Hydrol. 49:241–262.[Medline]

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This Article Abstract Figures Only Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Related articles in JEQ Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (8) Citing Articles via Google Scholar Google Scholar Articles by Singh, N. Search for Related Content PubMed PubMed Citation Articles by Singh, N. Agricola Articles by Singh, N. Related Collections Agricultural Pesticides Nitrogen Laboratory Column Studies Organic Compounds Water Pollution